Sunday, August 6, 2017

Construction - Temporary Protection

WARNING!  This post is surely the most boring one so far.  What makes it worth the effort, though, is that it could be a gift for any slow-paced DIY home-builder having to contend with the elements like we have to do here in the lower Midwest.

I have spent considerable time installing and maintaining temporary protection to keep the weather from degrading the bones and skin of the building before I could get the final roof and wall cladding installed. In the process, I have learned some things, good and bad, about temporary protection that might save others time and money. 

The pictures of the temporary covers start with a southeast view and rotate around the house counterclockwise to a southwest view.  Click on any pic to enlarge it.

Material Selection
Five materials for temporary protection come to mind.
Southeast view including east garage wall to the right
Six mil clear plastic sheeting is way too temporary. It allows UV rays to penetrate completely through its thickness so it starts coming apart in a matter of weeks during the hot summer. The consumer grade of tarpaulin degrades in the sun within a year or so.  First it starts leaking then begins coming apart in the wind. Housewrap such as Tyvec is often used for temporization but a web search suggests that UV damage undermines its water resistance under the cladding later -- and the amount of damage is directly proportional to the length of exposure. Therefore, it is only
Northeast view
material I have not tried. Six mil black plastic sheeting is a happier story. Only the surface is damaged by UV rays and at such a slow rate that it maintains its integrity for many months.  

My experience leads me to believe that, for wall sheathing, the best material for temporary protection is the wrap in which dimension lumber is shipped and stored. It repels water and is much tougher than my second choice, black plastic, making it ideal for use in windy conditions.  It is the only
North view
material discussed here that stays in place pretty well with staples. All the others rip loose easily, although tarps are a little better than plastic in this regard (at least when they are first installed). Since lumber wrap is usually white, it has the added advantage over black plastic of 
having a higher solar reflectance that keeps a building a little cooler in summer.  For this reason, I would make sure that it went onto the south and west walls if the
Northwest view
supply of lumber wrap was limited
. I would not use lumber wrap on the roof, however.  It typically has had a hard life and comes with many large and small holes that would have to be seriously patched for adequate protection.  Having said that, it would probably hold up to hail better than plastic. 

Sad Experience with 30# Felt Paper
For temporary roof protection, a sixth material, 30# felt, might seem to be a useful alternative, especially since it could be left eventually as underlayment for the final roof.
West view
 However, for whatever it is worth, my recent experience with it has been totally negative. Let me explain.

Back in the '70s, I used 30# felt for temporary protection of a large porch addition. The porch was protected by the felt for a couple of years while I waited to roof it in conjunction with roofing the garage. In retrospect, I think it held up as well as it did only because it was shaded most of the day.

In the most recent post, I made the case for using 30# felt as underlayment for standing seam metal roofing on our low-pitched roofs. So, based on my positive experience with the
Southwest view; notice that the white lumber wrap, as far
as it went, was used mostly on the hotter south walls
porch, I thought it made sense to make the leap to two layers of 30# felt, using the first layer as temporary protection until all of the roofs were ready for installation then using the second layer when the metal roof went on.  

We fastened the first layer of felt with roofing nails 18" or so apart and congratulated ourselves for getting the roof covered in time for the storm that night. Whoops! About a third of the felt was partially dislodged by the wind and had to be re-positioned and re-nailed as best we could considering that it now was badly wrinkled. As
30# felt before it was partially peeled off by high winds
for the second time despite the use of roofing cement
and extra nailing
we re-nailed it, we held the nails back from the edges to leave room for roofing cement in an attempt to seal down the edges. Unfortunately, by then the edges were so badly curled either by the storm or the hot sun or both and had enough memory to lift out of the cement before it had set. Or maybe roofing cement does not work well with felt.  In any case, we used another course of nails near the edges to augment the cement but by now the roof was becoming so irregular that I began to worry that a smooth profile of the metal roofing would be distorted.  To add to my frustration, another section of felt was dislodged with the next major storm and the hot sun caused the edges of the felt to lift in the areas that had been cemented but not been held down by a second course of nails..  

Altogether, we wasted about 14 man-hours trying to make the felt work.  In the end, it was
6 mil plastic sheeting battened down over the felt;
the Masonite sheets reinstalled to protect the plastic
while the overhang for the second story is being built;
notice the black duct tape patches on the lumber wrap
just easier to cover it with black plastic and call it a day.  My plans now are to remove the 30# felt entirely, pull the nails, lay down a new single layer of 30# as the metal roof goes on but protect it from the sun until it can be covered by the roofing. Then the metal will lay flat and smooth for the best appearance.

Batten Boards Are Essential
The secret to success with any temporary covering is to secure it with batten boards. Otherwise the wind finds its way under the covering and whips it loose immediately (plastic) or eventually (tarps) and, occasionally (lumber wraps).  And the boards have to be screwed down.  The whipping action of the covering in the wind easily works nailed battens loose from 1/2" sheathing, especially on the roof. It is bad enough that the boards end up on the ground but, if on the roof, the protruding nails cut holes in the covering as they bounce along. (I used bright nail for the battens; maybe ring shank nails would have held but been harder to remove later.)

My batten boards were sawed from salvaged 1 x 6 tongue and groove flooring that would have otherwise gone unused.  One and five-eights inch drywall screws are long enough as fasteners.  I have noticed that, when the boards are removed, the holes in the plastic under the battens made by the screws are enlarged by wind action.  Chances are that, despite the overlying board, some moisture reaches the sheathing but not sufficient quantity to make a difference.

Batten boards at right angles to the flow of the water on the roof have to be installed at a slight angle to redirect the flow.  On the roof, plastic needs to have all its peripheral edges battened down.  On sidewalls, the top is sheltered enough by the eaves to omit horizontal battening but the bottom should be secured with angled boards that do not dam the water running down the wall.  The horizontal boards can be eliminated entirely for lumber wrap as it is tough enough to stay put at the top and bottom with just staples between the vertical battens.

The covering is best installed when there is no wind.  It can then be spread out and tacked down with only enough staples to hold it flat while the batten boards are screwed to place. And a covering installed on a calm day will definitely be tighter and smoother.

Patching the Coverings
Garden variety duct tape works well for patching holes in any of the coverings except felt paper.  Anywhere plastic is stapled there is the potential for leakage so, if the covering is going to stay in place for a long time, I recommend minimizing the number of staples and then covering them with tape, knowing full well that they will cause leakage eventually. Lumber wrap always comes with holes some of which require serious patching.  For large holes, I cut the right size piece of scrap and taped it to place; for smaller holes, a piece of tape by itself worked fine.

The slap stapler is a very handy tool for most stapling jobs.  However, it scuffs holes in plastic sheeting when the handle is not held parallel with the plastic.  Increasingly, I have resorted to the traditional squeeze stapler for plastic sheeting in order to be more precise with staple placement and minimize the number of holes that have to be patched.

Honeydew Time
Temporary protection buys time.  In due time, I will be either removing it or folding it back out of the way a small section at a time as needed for such tasks as installing the second layer of sheathing for the north-sloping roof (as described in the prior post for the south-facing roof), building the overhang for the second story windows and installing the metal roof and metal siding.

The temporary protection also eliminates urgency, allowing me to take a week or two off for several major "honeydew" projects that have gone wanting for several months.